Ti2AlNb金属间化合物喷丸强化残余应力模拟分析与疲劳寿命预测

目的 研究经喷丸强化处理后Ti2AlNb材料表层残余应力的分布特征，并预测残余应力对材料疲劳性能的影响规律。方法 通过贴应变片逐层钻孔法，对使用喷丸强化处理后的Ti2AlNb试样进行残余应力测试分析，得到引入残余应力场各方面的测试数据，结合ABAQUS数值模拟方式，对比分析试验与模拟残余应力场结果，获取材料的最终残余应力梯度。利用FE-SAFE软件，通过叠加残余应力场的方式，预测喷丸强化前后试样的疲劳寿命。结果 在文中加工参数下，实验测试和软件模拟结果的重合度良好。喷丸强化可在Ti2AlNb金属间化合物靶材内引入300 MPa左右的最大残余压应力，深度达到了0.12 mm左右。材料表面塑性应变分布不均匀，且造成的塑性应变距表面深度可达0.1 mm。通过喷丸强化引入残余压应力，预测的Ti2AlNb材料疲劳极限可提高12%，高低周疲劳寿命均有明显的延寿效果。结论 验证了有限元数值模拟此材料喷丸强化的准确性和可靠性，得到了Ti2AlNb材料喷丸强化的残余应力场。由于塑性变形诱发机制的限制，喷丸造成塑性应变分布不均匀，塑性应变层深小于残余压应力层深。此外，强化后材料的疲劳性能显著提高，疲劳极限有可观的提升，且高低周疲劳均有较好的延寿效果。

Simulation of the Residual Stress and Fatigue Prediction of Ti2AlNb Intermetallic Compound under Shot Peening

The work aims to investigate the distribution characteristics of residual stresses on the surface layer of Ti2AlNb materials by shot peening, and predict the effect of residual stresses on fatigue performance. The residual stresses of Ti2AlNb specimens modified by shot peening were measured by the method of hole-drilling with strain gauge layer by layer. The test data of the residual stress field in various aspects were obtained. Combined with ABAQUS numerical simulation method, the results of the test and simulation of residual stress field were compared, and the residual stress gradient of the material was finally obtained. The fatigue life of the specimens before and after shot peening was predicted by FE-SAFE software by superimposing the residual stress field. Under the processing parameters, the experimental and simulation results coincided well. Shot peening could introduce maximum residual compressive stress up to 300 MPa in Ti2AlNb target and the depth of residual compressive stress layer was about 0.12 mm. The plastic strain distribution on the surface of the material was uneven, and the depth of plastic strain along the surface could reach 0.1 mm. After shot peening, residual compressive stresses were introduced so that the predicted fatigue limit of the material was raised by about 12%, and both the high and low cycle fatigue life was efficiently increased. The accuracy and reliability of FEM numerical simulation of shot peening of this material are confirmed, and the residual stress field of Ti2AlNb material is obtained. Due to the limitation of plastic deformation induced mechanism, shot peening results in uneven distribution of plastic strain, and the depth of plastic strain layer is less than that of residual compressive stress layer. Meanwhile, the fatigue property of the material is improved significantly, the fatigue limit is increased considerably, and both the high and low cycle fatigues have visible life extension effect.